Incidentally I do not look at an energy "crash" as desirable. Sounds more like Barbarism than socialism to me. This Does not mean it won't happen though. The fact that the technology is available at a cost in resources and labor we can afford does not in our short sighted system mean that it will be deployed.
This is why the environmental fight needs to be part of left struggle -- not merely to accommodate those attracted to the struggle, but to prevent disasters which -- to put it extremely mildly -- will be detrimental to any struggle for a more humane society. I think an attempt to predict either the exact date or nature of the disaster we face is case of precision exceeding accuracy. But I don't think any sensible person can doubt we are heading towards global catastrophe. I use catastrophe of course in the techincal sense that the NY Times uses it -- as a disaster that affects rich people. Environmental destruction is already a catastrophe for the poor-- but in conventional politics this is considered at most a "problem" , more likely a wild accusation made by fringe elements.